1. Field of the Invention
This invention relates to a method and apparatus for applying a split casing liner to the wall of a bore hole. The invention also relates to a split casing or liner suitable for sealing a portion of the wall of a bore hole.
2. Discussion of Related Art
Considerable time is lost when water or gas is struck while drilling for oil. Water, gas, or even oil might be found in the earth at a level above that level at which oil is expected to be found. Once the drill penetrates the stratum of the earth containing the water or gas, the water or gas is likely to seep into the bore hole through the wall thereof. This phenomenon is undesirable as the fluid seeping into the hole may interfere with the drilling process. Also, it may be desirable to conserve the gas, water or oil for recovery at a later time. For these reasons, it is often desired to seal the wall of the bore hole in regions where seepage occurs.
Various devices and methods have been employed to secure liners within subterranean bore holes. Many methods for doing so involve the use of explosives.
U.S. Pat. No. 2,214,226 to English discloses a technique for explosively expanding a deformable liner into contact with the wall of a bore hole. Alternatively, the technique and apparatus of the reference may be used to repair a casing previously installed within the hole. A liner having a diameter somewhat smaller than that of the casing or bore hole is inserted therein, and an explosive charge is detonated within the liner. The resulting force plastically deforms the liner in the region of the explosion, causing it to expand outwardly into contact with the casing or bore hole. However, the remaining portions of the liner retain its original, relatively small diameter, necessitating the use of a smaller drill bit following installation of the liner. Similarly, Lang, U.S. Pat. No. 3,167,122, discloses a radially crimped liner, expanded by explosive force and including a resilient sealing layer between the liner and a casing to be repaired. The method disclosed in this reference also comprises a subsequent deformation step to assure that the liner is fully expanded into contact with the casing.
Kinley, U.S. Pat. No. 3,191,677 dislcoses a method employing repeated explosions to drive an expander unit through a liner. Portions of the apparatus must be repeatedly withdrawn from the bore hole to be reloaded for successive detonations. U.S. Pat. No. 3,948,321 to Owen et al. uses explosive force for driving frustoconical wedges into a tubular liner, thus wedging the liner within a well casing.
It is, at best, extremely difficult to assure that a smooth and reliable seal will be achieved by any of the above methods utilizing explosives, as the forces involved are extremely difficult to control or regulate with any degree of accuracy.
U.S. Pat. No. 3,354,955 to Berry discloses a resilient liner for temporarily sealing openings in a well casing. The liner is inserted into the bore hold in a crimped condition, and is allowed to expand into contact with the casing. The device and method of this patent does not effect a reliable permanent seal of the casing, nor is it intended to do so.
Russian disclosure No. 588,346 illustrates a resilient helical steel strip wrapped tightly about a mandrel for repairing the wall of a bore hole. A second strip seals the seam between adjacent wraps of the helix. The device is inserted into a bore hole, and the strips are allowed to expand into contact with the walls thereof. The device apparently comprises no means for reliably securing it to the wall.